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                                                               EXECUTION VERSION

                                                                   EXHIBIT 10.22

                          SUPPLEMENTAL CREDIT AGREEMENT

      Supplemental Credit Agreement (this "Supplemental Credit Agreement") dated
as of June 17, 2004, among Seabulk International, Inc., a Delaware corporation
(the "Borrower") and Fortis Capital Corp. (the "Agent").

                              PRELIMINARY STATEMENT

      Pursuant to the Amended and Restated Credit Agreement, dated as of August
5, 2003, as amended on March 26, 2004 (the "Credit Agreement"), among Seabulk
International, Inc., (the "Borrower"), the Subsidiary Guarantors named therein,
the Released Subsidiary Guarantors named therein, Fortis, NIB Capital Bank N.V.
("NIB"), The Governor & Company of The Bank of Scotland and each other financial
institution which may hereafter execute and deliver an Assignment and Acceptance
with respect to the Credit Agreement pursuant to Section 10.11 thereof (any one
individually, a "Lender", and collectively, the "Lenders"), Fortis, as
administrative agent on behalf of the Lenders (when acting in its capacity as
administrative agent under any Transaction Document, herein referred to,
together with any successor administrative agent, as the "Agent") and as book
runner and as an arranger (when acting in such capacity, an "Arranger") and NIB,
as an arranger (when acting in such capacity, an "Arranger", and together with
Fortis, the "Arrangers"), the Lenders agreed to make the Facility available to
the Borrower, in accordance with the terms of the Credit Agreement. As a
condition to providing such Facility, each of the Lenders has requested that the
Subsidiary Guarantors, jointly and severally, guarantee the Obligations of the
Borrower under the Credit Agreement by entering into the Guarantee Agreement and
securing the Subsidiary Guarantors' obligations hereunder by granting to the
Agent, on behalf of the Lenders, a lien in, to and under the Collateral (as
defined herein). The Borrower has requested that the SEABULK RHODE ISLAND and
the SEABULK KENTUCKY (collectively, the "Released Vessels") owned by one of the
Subsidiary Guarantors be released from the Mortgage thereon and that the SEABULK
PUFFIN owned by the Assignor, a wholly-owned subsidiary of the Borrower, be
substituted therefor. In order to induce the Lenders to release the Released
Vessels, Offshore Marine Management International, Inc. ("OMMI") has agreed to
grant to the Agent, on behalf of the Lenders, a lien in, to and under the
SEABULK PUFFIN (the "New Vessel") and the Collateral related thereto so that the
New Vessel shall be deemed for all purposes a "Vessel" under the Transaction
Documents.

      All things necessary to make this Supplemental Credit Agreement a valid
agreement of the Borrower, OMMI and the other Subsidiary Guarantors in
accordance with its terms have been done.

      NOW, THEREFORE, and in consideration of the premises, it is mutually
covenanted and agreed, for the equal and proportionate benefit of the Agent and
each of the Lenders, as follows:

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                                                               EXECUTION VERSION

            (i) OMMI hereby confirms that it unconditionally and irrevocably
guarantees, jointly and severally, to the Agent and each of the Lenders (i) the
full and prompt payment of the principal of the Notes and the indebtedness
represented thereby and the L/C Obligations when and as the same shall become
due and payable, whether at the stated maturity thereof, by acceleration, call
for redemption or otherwise; (ii) the full and prompt payment of interest on the
Notes and the L/C Obligations when and as the same shall become due and payable
(including interest at the Overdue Rate on any part of the principal amount,
interest amount or other amount due under this Agreement and not paid when due);
(iii) the full and prompt payment of an amount equal to each and all of the
payments and other sums when and as the same shall become due, required to be
paid by the Borrower under the terms of the Credit Agreement and under each of
the other Transaction Documents to which it is a party and (iv) the full and
prompt performance and observance by the Borrower of the obligations, covenants
and agreements required to be performed and observed by the Borrower under the
terms of the Credit Agreement and under each of the other Transaction Documents
to which it is a party (items (i) through (iv), the "Subsidiary Guarantee
Obligations"). OMMI hereby confirms that it irrevocably and unconditionally
agrees that upon any default by the Borrower in the payment, when due, of any
principal of, interest on or other amounts (including amounts in respect of fees
and indemnification owing to the Agent or the Lenders) due under the Notes, the
Credit Agreement or any other Transaction Document, OMMI will promptly pay the
same within ten (10) days after the receipt of written demand therefore from the
Agent or any Lender. OMMI further confirms that it hereby irrevocably and
unconditionally agrees that upon any default by the Borrower in any of its
obligations, covenants and agreements required to be performed and observed by
the Borrower under the Credit Agreement and under each of the other Transaction
Documents to which it is a party, OMMI will effect the observance of such
obligations, covenants and agreements within ten (10) days after receipt of
written demand therefor from the Agent or any Lender.

      OMMI further confirms that it agrees that the Subsidiary Guarantee
Obligations may be extended or renewed, in whole or in part, without notice or
further assent from OMMI and that OMMI will remain bound under the Credit
Agreement notwithstanding any extension or renewal of any Subsidiary Guarantee
Obligation. OMMI confirms that it is subject to all the provisions of the Credit
Agreement applicable to a Subsidiary Guarantor. Without limiting the effect of
the foregoing, OMMI hereby agrees that it is hereby bound by the provisions of
Section 6.19 of the Credit Agreement relating to the assignment to the Agent as
security, and hereby grants to the Agent a security interest in (subject to the
provisions of the Assignment of Earnings and Insurances), all the freights,
hires, charters and Insurances to which such Additional Guarantor is entitled in
respect of the New Vessel and the other Vessels that it owns subject to the
Mortgages.

      SECTION 2. The Credit Agreement, as supplemented and amended by this
Supplemental Credit Agreement and all other Credit Agreements supplemental
thereto, is in all respects ratified and confirmed, and the Credit Agreement,
this Supplemental Credit Agreement and all Credit Agreements supplemental
thereto shall be read, taken and construed as one and the same instrument.

      SECTION 3. If any provision hereof limits, qualifies or conflicts with
another provision hereof which is required to be included in this Supplemental
Credit Agreement by any of the provisions of the Credit Agreement, such required
provision shall control.

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                                                               EXECUTION VERSION

      SECTION 4. All covenants and agreements in this Supplemental Credit
Agreement by OMMI shall bind its successors and assigns, whether so expressed or
not.

      SECTION 5. In case any provision in this Supplemental Credit Agreement
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

      SECTION 6. Nothing in this Supplemental Credit Agreement, expressed or
implied, shall give to any Person, other than the parties hereto and their
successors hereunder, and the Lenders any benefit or any legal or equitable
right, remedy or claim under this Supplemental Credit Agreement.

      SECTION 7. THIS SUPPLEMENTAL CREDIT AGREEMENT SHALL BE GOVERNED BY, AND
INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, WITHOUT
GIVING EFFECT TO PRINCIPLES OF CONFLICTS OF LAW.

      SECTION 8. All terms used in this Supplemental Credit Agreement not
otherwise defined herein that are defined in Appendix A to the Credit Agreement
shall have the meanings set forth therein.

      SECTION 9. This Supplemental Credit Agreement may be executed in any
number of counterparts, each of which shall be an original; but such
counterparts shall together constitute but one and the same instrument.

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                                                               EXECUTION VERSION

      WHEREOF, the parties have caused this Supplemental Credit Agreement to be
duly executed as of the date first written above.

SEABULK INTERNATIONAL, INC.,
 as Borrower,

         /s/ Alan R. Twaits
         ------------------------------------------
         Name:  Alan R. Twaits
         Title: Senior Vice President

FORTIS CAPITAL CORP.
 as Agent,

         /s/ Joshua Persky
         ------------------------------------------
         Name:  Joshua Persky
         Title: Vice President

         /s/ John Preneta
         ------------------------------------------
         Name:  John Preneta
         Title: Executive Vice President

OFFSHORE MARINE MANAGEMENT INTERNATIONAL, INC.,
hereby acknowledges and agrees to the terms,
conditions and provisions of the above
First Supplemental Credit Agreement,

         /s/ Alan R. Twaits
         ------------------------------------------
         Name:  Alan R. Twaits
         Title: Senior Vice President